Thixotropic shortening



United States Patent 3,360,376 THIXOTROPIC SHORTENING Robert D. Dobson, Greenhills, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Mar. 27, 1964, Ser. No. 355,438 7 Claims. (Cl. 99-418) ABSTRACT OF THE DISCLOSURE This invention relates to a thixotropic shortening. More particularly, it relates to a shortening which has the general characteristics of the solid state of matter when at rest and the general characteristics of the liquid state of matter when gently agitated.

It is an object of this invention to provide a shortening having a thixotropic character. It is a further object of this invention a method for producing a thixotropic shortening. As used herein, the'term thixotropic describes a shortening capable of existing in the solid state when at rest, the liquid state when gently agitated, and capable of readily and continuously passing from one state to the other.

An excellent thixotropic shortening having the above characteristics is made by appropriately combining from about 85% to about 90%, by weight, substantially completely liquid triglyceride base stock with from about 10% to about by weight, substantially completely hydrogenated triglyceride hardstock having a predominantly beta-phase crystallization tendency and subjecting the mixture to a carefully controlled crystallization process as set forth hereinafter.

The substantially completely liquid triglyceride base stock used in this invention should be liquid at room temperature, that is, it should not have more than about 1% solids at 70 F., not more than about 5% solids at 50 F., and essentially no solids at 80 F. and higher. For the purpose of this invention, the percent solids at any given temperature can be approximately determined with sufficient accuracy by the method described in 31 J. Amer. Oil Chemists Society, 98-103 (March 1954).

Suitable liquid triglyceride oils for the purpose of this invention can be derived, for example, from the naturallyoccurn'ng liquid vegetable oils, such as soybean, cottonseed, corn, olive, peanut, safflower, sesame seed, and rapeseed oils. Also, suitable liquid oil fractions can be obtained from palm oil, lard, and tallow, such, for example, as by graining or by directed interesterification, followed by separation of the oil. These oils can be partially hydrogenated, if desired, so long as the precent solids does not exceed the limits set forth hereinbefore.

Refined and bleached soybean oil, partially hydrogenated to an iodine value not lower than about 105 and, preferably, 107, is the preferred liquid triglyceride base stock of this invention. Soybean oils having iodine values greater than 120 can be used in this invention, but it is preferable to avoid their use because of their tendency toward oxidative instability.

The substantially completely hydrogenated triglyceride hardstock used in this invention should have an iodine value not greater than about 12. It should also have a predominantly beta-phase crystallization tendency as distinguished from an alpha phase or beta-prime phase. These types of polymorphic crystalline structures can be identified by their X-ray diffraction patterns and are described in US. Patents 2,52l,24l2, granted to Paul J. Mitchell, Jr., Sept. 5, 1950. Many of the ordinary glyceride fats can be crystallized in one or more of these phases which generally depends upon the particular processing treatment to which they are subjected.

Examples of trisaturated glycerides which have strong beta-phase-tending characteristics and which can be used in this invention are tristearin, tripalmitin and symmetrical palmitodistearin. Other suitable triglyceride hardstocks having strong beta-phase-tending characteristics can be derived from substantially completely hydrogenated fats and oils such as lard, sunflower seed oil, safflower seed oil, linseed oil, sesame seed oil, hazelnut oil, soybean oil, peanut oil, olive oil, and corn oil. A preferred beta-phase-tending triglyceride hardstock component is substantially completely hydrogenated soybean oil having an iodine value of about 8.

It is desirable to include in the hardstock component of the shortening of this invention for high-ratio baking purposes, a minor portion of monoand diglycerides of higher or long-chain saturated fatty acids having from about 12 to about 22 carbon atoms, such as monoand distearin. By way of example, suitable monoand diglycerides can be formed from substantially completely hydrogenated triglyceride superglycerinated to a monoglyceride content of about 40%.

When monoand diglycerides are used in the hardstock component, it is preferable to form the thixotropic shortening so that it comprises from about to about 88% by weight substantially completely liquid triglyceride base stock, from about 9% to about 14% by weight substantially completely hydrogenated triglyceride hardstock, and from about 1% to about 6% monoand diglycerides.

Antioxidants such as butylated hydroxytoluene, butylated hydroxyanisole, citric acid and methyl silicone can be employed in the shortening of this invention, also, for their antioxidant properties.

Briefly stated, the shortening of this invention is prepared as follows: the substantially completely liquid triglyceride base stock and the substantially completely hydrogenated hardstock are mixed together at a temperature sufficiently high to eliminate all crystalline material, for example, at a temperature higher than about 50 F. but less than about 200 F. The hot liquid mixture is rapidly cooled, in less than about 10 minutes and preferably in less than about 3 minutes, for example, in a conventional freezer or Votator, with agitation, to a temperature of from about 50 F. to about 70 F. in order to initiate fat crystallization therein. The chilled stock is then held without substantial addition or removal of heat and without agitation until crystallization is substantially complete. This can usually be accomplished in about 30 minutes. Thereafter, the material is permitted to transform at rest or under mild agitation at about F. to about F. until the fat crystals are converted to at least 95 beta-phase crystals, preferably having a fine particle size of from about 1 to about 12 microns. This can usually be accomplished in about an hour. The transformed stock is then heated over a period of a few minutes to about 1 hour to a temperature from about F. to about F. and then cooled over a period 3 of a few minutes to about 1 hour to a temperature of from about 90 F. to about 105 F. The resulting shortening stock is immediately packed into containers without further cooling or heating.

The term at rest is used herein to exclude the presence of agitation and fluid flow of the shortening. The term worked is used herein to define a condition whereby the shortening is not at rest but is stirred, shaken, or otherwise gently agitated.

At 70 F., the shortening of this invention has a worked" viscosity of from about 15,000 to about 35,000 centipoises and an at rest" viscosity not less than 10,000 centipoises higher than its worked viscosity. The viscosity can be easily determined by a descending Brookfield Helipath Viscometer for the at rest value, and by a stationary Helipath for the worked value.

A convenient container and dispenser for the thixotropic shortening of this invention is described in US. Patent 3,094,255, granted to Robert V. Burt, June 18, 1963.

The following example is illustrative of the process and product of the invention and, when taken together with other parts of this specification and the appended claims, will enable any person skilled in the art to which the invention appertains to devise many more examples which come within the scope of the claims.

EXAMPLE A mixture of 86 parts by weight refined, bleached soybean oil base stock having an iodine value of about 107, parts by weight refined, bleached soybean oil hardstock having an iodine value of about 8, and 4 parts by weight of a mono-, di-, and triglyceride mixture prepared from refined and bleached soybean oil hydrogenated to an iodine value of about 8 and superglycerinated to a monoglyceride content of about 40% was heated in a conventional mixing tank to 140 F. with agitation. Nitrogen gas (12% by volume) was injected into the melted oil mixture. The melted oil mixture was then pumped through a scraped wall heat exchanger (Votator) in which the oil was rapidly chilled with agitation to 60 F. in less than two minutes. The mixture which issued from the refrigerated heat exchanger was then allowed to pass by solid slippage without substantial addition or removal of heat and without agitation through a cylindrical tube six inches in diameter, five feet long, and having moderately heated walls (jacketed) at about 100 F. to 120 F. The chilled shortening took about 30 miuntes to pass through the tube during which time the heat of crystallization raised the temperature of the shortening to about 87 F. The shortening was then passed through a scraped wall heat exchanger which raised its temperature to about 105 F. and then into a tank where it was held for about 65 to 70 minutes with gentle agitation with a slow-sweep blade. During the 65 to 70 minute hold time, substantially all the shortening hardstock solids were converted to beta-phase crystals as determined by X-ray diffraction patterns. The transformed stock was then heated to 118 F. in a scraped wall heat exchanger (without melting the shortening) and held at that temperature for about 20 minutes. The shortening was cooled to about 99 F. and then throttled through a conventional homogenizing valve into containers with a pressure on the upstream side of the throttling valve of 250 p.s.i.g.

The resulting product was a stable, thixotropic shortening. It had a desirable opaque and brilliant white color which resembled a plastic shortening in appearance when at rest. Upon being slightly agitated by shaking, the shortening Was easily poured for measurement from a small narrow-mouthed container. It remained stable without settling out clear oil, solids, or large gas bubbles for storage periods up to six months at 70 F. to 90 F. The particle size of the bulk of the crystals as determined by microscopy ranged between 1 and 12 microns. The average particle size was about 3.7 microns. The Brookfield viscosity of the shortening at rest was 42,000 centipoises; and when the shortening was stirred and shaken, the viscosity was reduced to 27,000 centipoises. The shortening also remained pourable at temperatures as low as about 50 F.

Excellent quality cakes can be prepared from recipes using the thixotropic shortening of this invention with the convenience in dispensing and measuring of an ordinary liquid shortening. Suitable cake recipes for this purpose are found in U.S. Patent 2,874,053, granted to Victor Mills, Feb. 17, 1959.

Comparable quality thixotropic shortenings are obtained when other beta-phase crystal-tending hardstocks such as tristearin, tripalmitin, and symmetrical palmitodistearin are substituted for the substantially completely hydrogenated soybean oil in the above example, and When other substantially completely liquid triglyceride base stocks such as cottonseed oil, corn oil, and safiiower oil are substituted for the soybean oil in the above example.

What is claimed is:

1. A method of making an opaque thixotropic shortening having the appearance of a normally plastic shortening at temperatures below about 90 F. when at rest and being pourable at temperatures above about 50 F. when worked comprising (a) forming a mixture, at a temperature sutficiently high to eliminate all crystalline material, of from about to about by weight substantially completely liquid triglyceride base stock and from about 10% to about 15% by weight substantially completely hydrogenated triglyceride hardstock having an iodine value not exceeding about 12 and having a predominantly beta-phase crystallization tendency;

(b) rapidly cooling in less than about 10 minutes the hot liquid mixture with agitation to a temperature of from about 50 F. to about 70 F. to initiate fat crystallization;

(c) holding the chilled stock without substantial addition or removal of heat and without agitation until crystallization is substantially complete;

((1) converting the crystalline phase of the shortening stock to at least beta-phase crystals;

(e) heating the transformed stock over a period of a few minutes to about 1 hour to a temperature of from about F. to about F. without melting, and

(f) cooling over a period of a few minutes to about 1 hour the shortening stock to a temperature of from about 90 F. to about 105 F.

2. The method of claim 1 in which the crystalline phase of the chilled shortening stock is transformed to at least 95% beta-phase crystals without substantial agitation.

3. The method of claim 1 in which the crystalline phase of the chilled shortening stock is transformed to at least 95% beta-phase crystals without substantial agitation at a temperature of about 100 F. for about 60 minutes.

4. A method of making an opaque thixotropic shortenlng having the appearance of a normally plastic shortening at temperatures below about 90 F. when at rest and being pourable at temperatures above about 50 F. when worked comprising (a) forming a mixture, at a temperature sufficiently high to eliminate all crystalline material, of from about 85% to about 88% by weight substantially completely liquid triglyceride base stock, from about 9% to about 14% by weight substantially completely hydrogenated triglyceride hardstock having an iodine value not exceeding about 12 and having a predominantly beta-phase crystallization tendency, and from about 1% to about 6% monoand di-glycerides of long-chain saturated fatty acids having from about 12 to about 22 carbon atoms;

(b) rapidly cooling in less than about minutes the hot liquid mixture with agitation to a temperature of from about F. to about F. to initiate fat crystallization;

(c) holding the chilled stock without substantial addition or removal of heat and Without agitation until crystallization is substantially complete;

( d) converting the crystalline phase of the shortening stock to at least beta-phase crystals;

(e) heating the transformed stock over a period of a few minutes to about 1 hour to a temperature of from about F. to about F. without melting, and

(f) cooling over a period of a few minutes to about 1 hour the shortening stock to a temperature of from about 90 F. to about 105 F.

10 References Cited UNITED STATES PATENTS 2,521,242 9/ 1950 Mitchell 99118 15 2,815,285 12/1957 Holman et al. 99118 MAURICE W. GREENSTEIN, Prima Examiner. 

1. A METHOD OF MAKING AN OPAGUE THIXOTROPIC SHORTENING HAVING THE APPEARANCE OF A NORMALLY PLASTIC SHORTENING AT TEMPERATURES BELOW ABOUT 90*F. WHEN AT REST AND BEING POURABLE AT TEMPERATURES ABOUT ABOUT 50*F. WHEN WORKED COMPRISING (A) FORMING A MIXTURE, AT A TEMPERATURE SUFFICIENTLY HIGH TO ELIMINATE ALL CRYSTALLINE MATERIAL, OF FROM ABOUT 85% TO ABOUT 90% BY WEIGHT SUBSTANTIALLY COMPLETELY LIQUID TRIGLYCERIDE BASE STOCK AND FROM ABOUT 10% TO ABOUT 15% BY WEIGHT SUBSTANTIALLY COMPLETELY HYDROGENATED TRIGLYCERIDE HARDSTOCK HAVING AN IODINE VALUE NOT EXCEEDING ABOUT 12 AND HAVING A PREDOMINANTLY BETA-PHASE CRYSTALLIZATION TENDENCY; (B) RAPIDLY COOLING IN LESS THAN ABOUT 10 MINUTES THE HOT LIQUID MIXTURE WITH AGITATION TO A TEMPERATURE OF FROM ABOUT 50*F. TO ABOUT 70*F. TO INITIATE FAT CRYSTALLIZATION; (C) HOLDING THE CHILLED STOCK WITHOUT SUBSTANTIAL ADDITION OR REMOVAL OF HEAT AND WITHOUT AGITATION UNTIL CRYSTALLIZATION IS SUBSTANTIALLY COMPLETE; (D) CONVERTING TO CRYSTALLINE PHASE OF THE SHORTENING STOCK TO AT LEAST 95% BETA-PHASE CRYSTALS; (E) HEATING THE TRANSFORMED STOCK OVER A PERIOD OF A FEW MINUTES TO ABOUT 1 HOUR TO A TEMPERATURE OF FROM ABOUT 115*F. TO ABOUT 120*F. WITHOUT MELTING, AND (F) COOLING OVER A PERIOD OF A FEW MINUTES TO ABOUT 1 HOUR THE SHORTENING STOCK TO A TEMPERATURE OF FROM ABOUT 90*F. TO ABOUT 105*F. 